Qt Web Channel is a labs project that enables the creation of a WebSocket based channel between a web view and its QML/C++ container.

To build:
cd src
qmake
make
sudo make install

This would enable a QML import, which can be imported as such:
import Qt.labs.WebChannel 1.0

and then instantiated:
    WebChannel {
        id: webChannel

        onExecute: {
        }
    }

A new WebChannel then generates a secret URL, that can be used from within an HTML page as a loaded script.

QML:
WebView {
    id: webView
    url: "index.html?webChannelBaseUrl=" + webChannel.baseUrl;
}

HTML:
<script type="text/javascript" src="qrc:///qwebchannel/webchannel.js"></script>
<script type="text/javascript" src="qrc:///qwebchannel/qobject.js"></script>
<script type="text/javascript">
    var baseUrl = (/[?&]webChannelBaseUrl=([A-Za-z0-9\-:/\.]+)/.exec(location.search)[1]);
    var webChannel = new QWebChannel(baseUrl, function(channel) {
        // channel is connected, send data!
    });
</script>

This would invoke a function named createWebChannel (or any other name passed in the URL), that would receieve as a parameter the web channel object.
That object can be used to execute commands:

HTML
webChannel.exec("command", function(result) { ... });

QML
WebChannel {
     onRawMessageReceived {
         if (requestData == "command") { sendRawMessage("..."); }
     }
}

or subscribe to events:

HTML
webChannel.subscribe("myEvent", function(eventData) { ... });

QML
webChannel.sendMessage("myEvent", "...");

See examples for further details.